Cooked Algae Transforms into Crude Oil

Michigan Engineering researchers can "pressure-cook" algae for as little as a minute and transform 65% of the organisms into biocrude.

Oct 31, 2012

To make their one-minute biocrude, Phil Savage, an Arthur F. Thurnau professor and a professor of chemical engineering at the University of Michigan and Julia Faeth, a doctoral student in Savage's lab, filled a steel pipe connector with 1.5 milliliters of wet algae, capped it and plunged it into 1,100-degree Fahrenheit sand. The small volume ensured that the algae was heated through, but with only a minute to warm up, the algae's temperature should have just grazed the 550-degree mark before the team pulled the reactor back out.

"By reducing the reactor volume, the cost of building a biocrude production plant also decreases," Faeth said, though both she and Savage cautioned that they couldn't say for sure whether the new method is faster and cheaper until the process is further developed.

Current commercial makers of algae-based fuel first dry the algae and then extract the natural oil. But at over $20 per gallon, this fuel is a long way from the gas pump. One of the advantages of the wet method is that it doesn't just extract the existing fat from the algae—it also breaks down proteins and carbohydrates. The minute method did this so successfully that the oil contained about 90% of the energy in the original algae.

Before biocrude can be fed into the existing refinery system for petroleum, it needs pre-refining to get rid of the extra oxygen and nitrogen atoms. The Savage lab is developing better methods for this leg of biofuel production, breaking the record with a biocrude that was 97% carbon and hydrogen earlier this year.

Once producing biofuel from algae is economical, researchers estimate that an area the size of New Mexico could provide enough oil to match current U.S. petroleum consumption. Unlike corn produced for ethanol, good farmland isn’t needed for algae to grow; it thrives in brackish ponds instead.

The research, "The Effects of Heating Rate and Reaction Time on Hydrothermal Liquefaction of Microalgae," was funded by the Emerging Frontiers in Research and Innovation program of the National Science Foundation. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.